Comprehensive understanding the promoting effect of Dy-doping on MnFeOx nanowires for the low-temperature NH3-SCR of NOx: An experimental and theoretical study

Recently, Mn-based catalysts doped/modified by rare earth elements for the selective catalytic reduction (SCR) of NOx with NH3 are becoming a new research hotspot. In current work, Dy-doped MnFe oxides with the morphology of one-dimensional nanowire are successfully prepared by using electrospinning method for the first time, and the catalytic performances for the NH3-SCR of NOx are investigated in detail. It is found several positive factors are introduced due to the doping of Dy with an appropriate amount, such as the enhanced surface Mn4+ concentration and surface chemical adsorption of oxygen, the increased adsorption capacity for NH3 and NO. Theoretical calculation reveals that the Dy-doping causes the larger depletion of electron density of mainly O atoms on the surface of MnFeDy than that of MnFe case, which energetically favors the adsorption of NH3 and NO molecules. Our results fully confirm that Dy is an effective doped element of Mn-based catalysts for developing SCR catalysts with excellent low-temperature de-NOx performance.